Material handling method and apparatus

ABSTRACT

A method of and apparatus for handling sheet material including a peg conveyor for supporting and advancing a plurality of spaced, generally upright sheet articles in combination with a rack having spaced pegs and carried on a mobile lift apparatus for stripping the articles from said conveyor onto said rack or for depositing sheet-like articles from a loaded rack onto a conveyor or other article support system.

This is a division of application Ser. No. 121,795, filed Feb. 15, 1980,now U.S. Pat. No. 4,320,826.

BACKGROUND OF THE INVENTION

This invention relates generally to the material handling art and, moreparticularly, to a method of and apparatus for handling glass sheetarticles, such as automotive windshields for example.

In the production of glass products, such as present day automotivewindshields for example, it is common practice to store and transportsuch windshields on racks between the various fabricating stages such asthe pattern scoring, glass breaking-out, edge finishing, bending andtempering, and laminating operations for example. Much of the transferof the glass sheets between the racks and the production line of theparticular phase of production being conducted is done manually, usuallyby at least two attendants at each station who remove the sheets fromthe racks at the loading end of a particular line operation and anotherpair of attendants at the unloading end thereof to remove the processedglass sheets from the production line onto other racks. It can bereadily appreciated that such manual operations seriously impairefficiency and productivity in a mass production operation, and therebyincrease production costs. Also, the attendant fatigue in performingsuch arduous tasks often results in careless glass handling withconsequent scratching, chipping or breaking of the glass products,further encumbering production and adding materially to productioncosts.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to obviatethe above-noted shortcomings by providing a new and useful method of andapparatus for automatically handling sheet products rapidly, smoothly,and with the precision essential in an automated glass fabricationprocess.

Another object of this invention is to provide a new and useful storagerack for stripping or depositing a plurality of sheet productssimultaneously from or onto a support system, such as a conveyor forexample.

Still another object of the present invention is to provide on theforegoing rack a plurality of spaced rows of specially constructed pegassemblies for supporting a plurality of sheets in an upright, spacedrelation.

Yet another object of this invention is to provide a new and improvedpeg conveyor for receiving and accumulating a series of sheet articlesthereon for subsequent removal.

A further object of this invention is to employ the foregoing storagerack in combination with the above mentioned accumulating transferconveyor to transfer a series of sheet products simultaneouslytherebetween.

Still a further object of the present invention is to provide in theforegoing combination means for precisely orienting the rack andaccumulating conveyor relative to each other in order to effect thearticle transfer.

The foregoing and other objects, advantages, and characterizing featuresof the present invention will become clearly apparent from the ensuingdetailed description thereof considered in conjunction with theaccompanying drawings wherein like reference characters denote likeparts throughout the various views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 4 are schematic views illustrating the material handlingapparatus of this invention, and which includes an accumulating conveyorand rack arrangement shown in various relative operational positions;

FIG. 5 is a side elevational view of the material handling apparatusconstructed in accordance with this invention;

FIG. 6 is a top plan view of the apparatus of FIG. 5;

FIG. 7 is a fragmentary, end elevational view, looking in the directionof arrows 7--7 of FIG. 5, of a chain relaxing means used in conjunctionwith this invention;

FIG. 8 is a fragmentary, side elevational view of the accumulatingtransfer conveyor of this invention, looking at the outer face of oneside thereof;

FIG. 9 is a vertical sectional view, on an enlarged scale, taken alongline 9--9 of FIG. 8;

FIG. 10 is a fragmentary, side elevational view, looking in thedirection of arrows 10--10 of FIG. 9 or at the inner face of one side ofthe accumulating transfer conveyor;

FIG. 11 is a fragmentary, perspective view of a pair of upright pegassemblies mounted on the conveyor drive chain;

FIG. 12 is a perspective view of a storage rack constructed inaccordance with this invention and used in conjunction therewith;

FIG. 13 is a side elevational view of the rack of this invention shownsupported on a mobile lift apparatus, also constructed in accordancewith this invention;

FIG. 14 is a top plan view of the rack and mobile lift apparatus of FIG.12, with portions thereof broken away for the sake of clarity;

FIG. 15 is an end elevational view of the rack and mobile lift assemblyof FIG. 13, looking in the direction of arrows 15--15 of FIG. 13;

FIG. 16 is an enlarged, fragmentary, perspective view of the pegarrangement mounted on the rack of FIG. 12; and

FIG. 17 is a horizontal sectional view, on an enlarged scale, takenalong line 17--17 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the illustrative embodiment depicted in theaccompanying drawings, there is shown schematically in FIGS. 1-4 a sheethandling apparatus, comprehensively designated 20, especially adaptedfor use in handling paired sheets of glass, such as are utilized in theformation of automotive windshields and the like. The apparatus 20includes an accumulating transfer conveyor, generally designated 21 andhereinafter often referred to as a "peg" conveyor, adapted to receivepaired sheets of bent or curved glass as a unit, identified as W, froman input or delivery conveyor 22 and to advance the same along conveyor21 until a predetermined number of such units W have been accumulatedthereon. The conveyor 21 is then indexed to shift the accumulated unitsW rearwardly to a given position and is momentarily stopped at suchposition. In the meantime, an empty rack, generally designated 23, isadvanced by a run-in conveyor 25 into position above a mobile liftapparatus 26. The apparatus 26 is operative to lift the empty rack 23off conveyor 25 to a position slightly thereabove and then movelongitudinally along tracks 27 to advance the rack 23 to a preciseposition beneath the active run of conveyor 21. The rack 23 is thenraised by apparatus 26 to strip or lift the accumulated glass units Woff conveyor 21 to an elevated position thereabove. The mobile liftapparatus 26 is then returned via tracks 27 to its initial startingposition, carrying the loaded rack 23 therewith. Apparatus 26 is thenactuated to lower the loaded rack 23 onto conveyor 25, which can bedriven in a reverse direction to convey or otherwise remove the glassladen rack 23 to another station for storage or for unloading onto afurther glass processing station.

While the apparatus 20 of this invention is particularly suited forhandling paired sheets of glass, such as the complementary inboard andoutboard sheets of a windshield for example, it should be understoodthat apparatus 20 is in no way restricted thereto, but has utility inhandling single sheets of glass or any other somewhat rigid sheetmaterial.

Referring now to FIGS. 5-11, the accumulating transfer conveyor 21comprising a base frame 28 including a pair of longitudinally extending,transversely spaced beam members 29 extending substantially the lengthof the conveyor 21 and suitably supported on upright posts or legs 30. Astructural cross member 31 extends between and is rigidly secured at itsopposite ends to the beam members 29 at one end of conveyor 21 while theother end of the conveyor is left open to permit passage of the mobilelift apparatus 26 and rack 23 thereinto between the beams 29. Conveyor21 includes a pair of laterally spaced, endless drive chain assemblies32 located along the opposite sides of conveyor 21 and entrained aboutlaterally spaced drive sprockets 33 located at one end of the frame andidler sprockets 35 disposed at the other end of the frame 28. The drivesprockets 33 are rigidly secured to a common drive shaft 36 adjacent theopposite ends thereof and which is suitably journalled for rotation inspaced bearing blocks 37. The idler sprockets 35 are mounted on idlerstub shafts 38 journalled for rotation in mounting bars 40 suitablykeyed or otherwise fixedly secured to the upper ends of legs 30. Thedrive shaft 36 is intermittently rotated by gear-motor assembly 41suitably mounted on the frame 28.

Each of the drive sprockets 33 and idler sprockets 35 is of the dualtype having two rows of laterally spaced teeth to accommodate thelaterally spaced drive chains 32a and 32b (FIGS. 6 and 9) of each drivechain assembly 32. As is well known, each chain 32a, 32b, includes theusual series of opposed links 43 connected together by pins 45 to forman endless chain, the openings between opposed links 43 receiving theteeth of the sprockets so as to be driven thereby. In the illustrativeembodiment depicted in FIG. 9, the pins 45 also carry rollers 46supported on guide rails 47 secured to the upper flanges 48 of beams 29.

In addition to the dual drive chains 32a and 32b, each drive chainassembly 32 includes a series of paired angle members 50 (FIGS. 9 and11) connected at their vertical legs to the pins 45 of both drive chains32a and 32b for movement therewith. The horizontal portions 51 of anglemembers 50 support a peg assembly, generally designated 52, comprised ofa base member 53 fixedly secured to the angle member portions 51 andsupporting a pair of upstanding, rod-like metal pegs 55a and 55b. Thesepegs 55a and 55b extend upwardly at a slight angle to a true verticaland converge at their upper ends for receiving a common cap 56 (FIG. 8),preferably formed of nylon, to preclude scratching or breakage of theglass surfaces bearing thereagainst during run-in loading of theconveyor 21 and advancement therealong. The use of dual pegs 55a and 55boriented in a slight inclination to each other offers rigidity andstrength, avoiding bending or flexing thereof during use. Because of theprecise orientation of these pegs necessary to effect a smooth and easytransfer of articles, as will hereinafter be described, it is importantthat they resist flexing and/or bending so that their attitudes remainconstant during repeated cycling.

Each peg assembly 52 also includes an L-shaped pad, generally designated57, removably secured, as by an affixed mounting plate 58, to the basemember 53 by suitable fasteners 60. The pad 57 is located between pegs55b and 55a of adjacent peg assemblies 52 for receiving and supportingthe lower edges of the paired sheets forming unit W and is formed of aresiliently yieldable plastic material, preferably urethane, forpreventing chipping or breakage of the glass sheets when deposited andcarried thereon. The pad 57 includes a raised horizontal portion 61 uponwhich the glass sheets rest, a lower horizontal portion 61a, and anupright portion 62 defining an abutment face 63 just forwardly of peg55a of the adjacent assembly 52 to avoid engagement of the glass sheetswith the latter. A groove 64 is formed in the horizontal portion 61 ofpad 57 for receiving peg 55b. The pegs 55a and 55b of each assembly 52are slightly laterally offset (FIGS. 9 and 11) from each other toaccommodate the curvature of the windshield unit W.

The drive chain assembly 32 described above is duplicated along theother side of conveyor frame 28 so that each pair of pegs 55a and 55b islaterally aligned with another pair of pegs 55a and 55b along a lineparallel to the shaft 36 and the common axis of shafts 38. Eachlaterally aligned pair of peg assemblies 52 is spaced longitudinallyfrom the adjacent pair of peg assemblies 52 sufficiently to supportivelyreceive and readily accommodate a curved windshield unit W therebetweenand the pad assembly 57 associated with each adjacent pair of pegasemblies 52 spans the space existing therebetween to provide aresiliently yieldable support for the bottom edges of the paired sheetsforming the unit W. The peg conveyor 21 is intermittently driven orindexed and temporarily halted at regular, precise intervals to presentsuccessive open spaces between successive pairs of laterally aligned pegassemblies 52 to receive individual units W from delivery conveyor 22and advance the same step by step along the conveyor 21. To this end,motor 42 is braked or deenergized to interrupt movement of the drivechain assemblies 32 at precise intervals each time an open space betweensuccessive peg assemblies 52 is presented to the trailing end ofconveyor 22. At least one limit switch LS-1, mounted on base frame 28adjacent the trailing end of conveyor 22, is positioned in the path ofmovement of an oncoming windshield unit W. The leading edge of anadvancing unit engages the switch LS-1 to complete a circuit energizingmotor 42 to index the drive chain assemblies 32 a distance presentingthe next open space to conveyor 22. An encoder 65, mounted on base frame28 and operatively connected to drive shaft 36, records each unit Wreceived on peg conveyor 21. When a predetermined number of units W hasbeen accumulated on conveyor 21, the encoder 65 becomes operative togenerate a signal stopping delivery conveyor 22 and controlling motor 42to shift or index the peg conveyor 21 rearwardly to a given position, asdetermined by another limit switch (not shown) for example, whereat theconveyor 21 is stopped at the desired position to enable the rack 23 tosubsequently lift all the units W off conveyor 21. It should beappreciated that the units W must be precisely located on conveyor 21relative to the underlying rack 23 in order to effect the above transferand then, even the slightest misalignment, such as might be caused bydrive chain wear and the like, could interfere with the properconveyor-to-rack transfer.

In order to assure accurate disposition of the units W on conveyor 21relative to rack 23 upon elevation of the same, a plurality of drivechain centering assemblies 66 are provided along opposite sides of theconveyor to locate the respective drive chain assemblies 32 and therebypeg assemblies 52 in the same identical position after each conveyorshifting operation. In order to avoid confusion, the term "shifting", asused in this description, refers only to the movement of the conveyor 21upon the accumulation of a predetermined number of units W thereon asopposed to the intermittent movement (indexing) of the conveyor inpresenting successive open spaces between peg assemblies 52 forreceiving individual units W thereon. As best shown in FIGS. 8-10, eachcentering assembly 66 comprises a centering rack 67 disposed beneath theassociated drive chain assembly 32 and extending lengthwise thereof. Therack 67 includes a pair of side rails 68, each having longitudinallyspaced, arcuate, semi-circular grooves 70 complementary to thecircumferential configuration of rollers 46. The rack 67 is adapted tobe raised upwardly with the grooves 70 engaging about rollers 46 toaccurately position chain drive assembly 32 upon completion of theconveyor indexing operation.

The means for raising each centering rack 67 includes an actuatingcylinder 71 mounted on the lower flange of beam 29 and having the usualreciprocating piston (not shown) connected to a piston rod 72. The upperend of the piston rod 72 engages an extension 73 forming a part of alift arm 75 located on the outer side of the beam web and rigidlysecured to a pivot pin 76 journalled in a bearing sleeve 77 mounted inthe web of beam 29. A bell crank 78, located on the other or inner sideof the beam web, also is mounted on the pivot pin 76 for pivotalmovement therewith.

This lift arm-bell crank arrangement is also provided at the other endof centering rack 67 and similar reference numerals are used to identifythe same parts. The longitudinally spaced bell cranks 78 on the innerside of the beam web are operatively connected together by a link 80pivotally connected at its opposite ends to the bell cranks 78. The liftarms 75 and bell cranks 78 are provided with actuators 81 in the form ofthreaded rods and nuts to engage the lower ends of lifter pins 82,respectively, secured at their upper ends to the centering racks 67.Thus, actuation of cylinder 71 to raise piston rod 72 pivots the liftarms 75 and bell cranks 78 in unison to effect raising of the centeringrack 67 into engagement with the rollers 46 of the chain drive toprecisely orient the same in the desired location for subsequent articletransfer from the conveyor 21. A pair of spring-biased devices 83 areprovided on the rack 67 for returning the same to its lower positionupon retraction of the piston rod 72 after completion of the chaincentering operation.

In the illustrative embodiment depicted in the drawings, three suchchain centering assemblies 66 are utilized on each side of the pegconveyor 21 and are located in lateral alignment with the other threeassemblies 66. The laterally aligned pairs of assemblies 66 are actuatedin succession, starting at the powered end of the conveyor 21 (the leftas viewed in FIG. 5), to precisely position the peg assemblies 52 justprior to effecting the transfer of the accumulated units W from conveyor21 onto rack 23.

Means are provided for relaxing the chain drive assemblies 32 prior tocentering the same. As shown in FIGS. 5 and 7, such means include apivotal lift frame 85 at each side of conveyor 21 and which is comprisedof a pair of elongated angle members 86 pivotally mounted, as at 87 inFIG. 5, to the underside of beam 29 and which carry at their other endsa pair of support arms 88, respectively, welded or otherwise fixedlysecured to the frame angle members 86. The arms 88 support stub shafts90 on which is mounted a double take-up sprocket 91 having laterallyspaced sprockets 91a and 91b connected together by a common hub 92therebetween and engageable with the drive chains 32a and 32b,respectively, of the drive chain assembly 32. An extensible piston rod93 of an actuating cylinder 95 secured to the underside of beam 29 isconnected to a transverse pin 96 extending between and connected to thesupport arms 88. The piston rod 93 normally is extended to urge sprocket91 against the drive chain and thereby apply tension thereto. However,just prior to raising chain centering racks 67 into engagement with therollers 46 of the drive chain assemblies 32, the piston rod 93 isretracted to provide sufficient slack in the drive chain for slightmovement thereof when engaged by the racks 67.

A significant feature of this invention resides in the use of storagerack 23, which not only supports a plurality of sheets for storage ortransport from one place to another, but also is employed in strippingand depositing an accumulated series of sheets off and onto a conveyorsystem. The rack 23 includes a frame 100 comprised of a pair ofelongated side members 101 and 102 of generally rectangular, hollowshape in cross section and a series of structural cross members 103 alsoof generally rectangular, hollow shape in cross section extendingbetween and connected at their opposite ends to side members 101 and102. Elongated supports 105 are welded or otherwise fixedly secured tothe upper surfaces of side members 101 and 102.

Each of the elongated supports 105 has rigidly mounted to the topsurface thereof a longitudinal row of spaced, upright peg assemblies106. Each assembly 106 comprises a pair of rod-like pegs 106a and 106bextending upwardly at a slight angle to a true vertical and convergingat their upper ends for receiving a common cap 107, preferably formed ofnylon or any other suitable resiliently yieldable, elastomeric materialto protect the surfaces of the glass sheets during the loading andunloading thereof onto and off the rack 23. The peg assemblies 106 ofeach elongated support 105 are laterally aligned with the peg assemblies106 of the other support 105 and the longitudinal spacing betweenadjacent laterally aligned sets of peg assemblies 106 is sufficient tosupportively receive the greatest curvature of windshield unit Wexpected to be handled.

As best shown in FIG. 16, a pad 103 is mounted on the elongated support105 between each peg 106b and 106a of longitudinally adjacent pegassemblies 106 for receiving and supporting the lower edges of the glasssheets and is formed of resiliently yieldable plastic material,preferably urethane, for preventing chipping and breakage of the sheets,as well as providing a friction surface to avoid longitudinal or lateralslipping of the sheets thereon during transport. Each pad 108 is formedwith opposite semi-circular grooves 110 for accommodating the lower endsof pegs 106b and 106a of adjacent peg assemblies 106.

As earlier mentioned, a mobile lift apparatus 26 is employed to carrythe rack 23 for movement in both a horizontal and vertical direction foreffecting the transfer of units W from conveyor 21 onto the rack 23. Asbest shown in FIG. 5 and FIGS. 13-15, the lift apparatus 26 comprises agenerally rectangular base frame 111 formed of suitable longitudinallyand transversely extending structural members 112 and 113, respectively.The frame 111 is provided with a pair of drive wheels 115 mountedadjacent the ends of a drive shaft 116 journalled for rotation in thelongitudinal structural members 112. Also, a pair of idler wheels 117are mounted on a shaft 118 suitably mounted on the side members 112. Onewheel of each pair has a peripheral V-groove 120 adapted to ride on theinverted V-shaped track 27 while the other wheel of each pair has anannular surface adapted to roll on a flat surface rail 121 (FIG. 15).The means for rotating drive shaft 116 includes an electric motor 122having an output shaft 123 suitably connected, as by a chain andsprocket arrangement 125, to a gear reduction box 126, in turn connectedvia sprocket and chain arrangement 127 to the drive shaft 116.

The apparatus 26 includes a lift platform 128 having side members 130and end members 131 to form a rectangular structure for supporting arack 23. The lift platform 128 is supported from the base frame 111 bytwo pairs of scissor links 132 and 133, respectively, at opposite endsof the apparatus 26. The links of each pair are pivoted centrally on apivot pin 135. The upper ends of the links 132 are pivotally mounted, asat 136 in FIG. 5, on the sides of platform 128 adjacent one end thereofwhile the lower ends of links 132 carry rollers 137 which run intrackways 138 along the sides of the base frame 111. The lower ends ofthe links 133 are pivotally mounted, as at 140 in FIG. 5, on the sidesof base frame 111 adjacent one end thereof and the upper ends of links133 carry rollers 141 guided in trackways 142 along the sides of thelift platform 128.

Lugs 143 are mounted on the lower halves of the laterally spaced scissorlinks 132 to support a pivot shaft 145 to which is connected the headend of an actuating cylinder 146. The piston rod 147 of cylinder 146 ispivotally mounted on a pivot shaft 148 connected at its opposite ends tothe upper halves of scissor links 133. Accordingly, extension andretraction of the piston rod 147 is effective to swing the links 133upwardly and downwardly to raise and lower the lift platform 128.

As earlier explained, the mobile lift apparatus 26 is operative to carryan empty rack 23 beneath the accumulating transfer conveyor 21 and raisethe rack to lift a plurality of windshield units W off conveyor 21. Inorder to assure proper positioning of the rack 23 to effect thistransfer, means are provided to accurately orient the rack 23 relativeto conveyor 21. As best shown in FIGS. 5 and 17, such means comprises anadjustable locator stop 150 having an abutment pad 151 attached to thedistal end of a threaded rod 152. The pad 151 is adapted to be engagedby an inverted L-shaped bumper 153 rigidly secured onto the leadingtransverse member 113 of frame 111.

In order to maintain the lift apparatus 26 in the desired position, thebumper 153 projects below and laterally outwardly of lift frame 111 forengagement by a hook 155 forming a part of an L-shaped bracket 156attached to the distal end of a piston rod 157 of an actuating cylinder158. Cylinder 158 is pivotally mounted at its head end on an upstandinglug 160 extending upwardly from a support base 161. The hook 155 isprovided with a pin 162 projecting laterally from the opposite sidesthereof and adapted to ride on guides 163. Each guide 163 has a straightplanar surface 165 and an inclined surface 166. The piston rod 157 isnormally extended with the pin 162 resting on surfaces 166, so that hook155 is in a lowered, out-of-the-way position. As the lift frame 111approaches the end of its travel beneath conveyor 21, an L-shapedactuator 167 mounted on bumper 153 engages a limit switch LS-2 tocomplete an electrical circuit (not shown) controlling operation ofcylinder 158. The piston rod 157 and thereby hook 155 is retracted,moving the latter upwardly and inwardly toward the bumper 153 until itengages therebehind to press and lock the lift apparatus 26 against stoppad 151, thereby positioning rack 23 in the desired location relative totransfer conveyor 21.

As best shown in FIGS. 13-15, the run-in conveyor 25 is utilized todeliver racks 23 one at a time to the mobile lift apparatus 26. Conveyor25 includes a frame 170 comprised of a plurality of laterallyspaced-apart and aligned columns 171 adapted to support conveyor wheels172 thereon. Each of the wheels 172 is formed with a peripheral flange173 and is mounted on the inner end of a shaft 175 suitably journalledfor rotation on the associated column 171. Pinions 176, driven by anendless drive chain 177, are rigidly secured onto the other or outerends of one row of drive shafts 175. This drive chain 177 is entrainedabout all the pinions 176 of the several wheels 172 along one side ofthe conveyor 25 for rotating the same in unison at the same speed toconvey racks 23 thereon. The wheels 172 along the other side of theconveyor 25 are idler wheels.

The drive for chain 177 includes an electric motor 178 connected to asuitable source of electrical power (not shown). The motor is connected,via gear reduction box 180, to an output shaft 181 having a drivesprocket 182 secured thereon. A drive chain 183 is entrained about drivesprocket 182 and a driven sprocket 185 rigidly mounted on a driveextension 186 formed on one of the drive shafts 175.

The racks 23 are guided in their vertical movement by angled guideplates 187 welded or otherwise fixedly secured to brackets 188 mountedon plates 189 supported on the columns 171. As shown in FIG. 15, theoutside lateral dimension of each rack 23 is just slightly smaller thanthe distance between opposed flanges 173 of laterally aligned wheels 172and the lower ends of the angled guide plates 187.

The run-in conveyor 25 is operated to deliver a rack 23 to a positionslightly above the lift platform 128 of mobile lift apparatus 26 when inits collapsed position. The advancing rack 23 engages a roller stop 190to accurately position the rack 23 relative to the underlying liftplatform 128. At the same time, the leading end of the rack 23 engagesand actuates a limit switch LS-3 to close a circuit controllingoperation of actuating cylinder 146 to extend piston rod 147 and raiselift platform 128. The platform 128 moves upwardly between side members101 of the rack 23 into engagement with the underside thereof to liftrack 23 upwardly off conveyor wheels 172. The apparatus 26 is then movedlongitudinally on tracks 27 into its predetermined position beneathaccumulating transfer conveyor 21 to effect the article transfer.

The mode of operation of the sheet handling apparatus 20 of thisinvention is as follows:

Paired bent glass sheets forming the windshield unit W are delivered atspaced intervals from a glass processing station, such as a bendingfurnace for example or any other material handling or processingapparatus, on delivery conveyor 22 to the accumulating transfer conveyor21. The conveyor 21 is intermittently operated and indexed to move thepeg assemblies 52 thereof in a step by step, endless orbital path in atimed cyclic relation with conveyor 22 for presenting a free open spacebetween adjacent pairs of laterally aligned peg assemblies 52 at thedischarge end of delivery conveyor 22. The conveyor 22 advances the unitW horizontally into such space and onto a pair of now horizontallyextending, laterally spaced peg assemblies 52. When the leading edge ofthe unit W engages the switch LS-1, motor 42 is energized to driveconveyor 21 and these movable peg assemblies, in the course of theirorbital travel, swing the unit W upwardly into an upright position. Thelower edges of the unit W settle against the pad assemblies 57 whileother portions of the unit W rest against caps 56. As the unit W isswung upwardly by the peg assemblies 52, the next succeeding open spacetherebetween becomes aligned with the trailing end of delivery conveyor22. The conveyor 21 is then momentarily stopped to receive the next unitW. When a predetermined number of such units have been accumulated onpeg conveyor 21, as determined by encoder 65, the conveyor 21 is shiftedrearwardly to a predetermined position and stopped with a pair oflaterally aligned drive chain rollers 46 in vertical alignment with thefirst grooves 70 of the first pair of laterally aligned chain centeringassemblies 66.

Upon stoppage of the accumulating transfer conveyor 21, cylinders 95 areactuated to retract their respective piston rods 93 and thereby removethe bias on the drive chain assemblies 32 along both sides of theconveyor to provide slack therein. Thereupon, the several pairs ofcylinders 71 are sequentially operated to raise the three pairs ofcentering racks 67 in succession into engagement with rollers 46 of thedrive chain assemblies 32. This precisely orients the peg assemblies 52and thereby the windshield units W in the exact location required forsubsequent removal by rack 23.

In the meantime, mobile lift apparatus 26 is positioned beneath run-inconveyor 25 with the lift platform 128 in its lowermost position. Anempty rack 23, deposited or otherwise conveyed to run-in conveyor 25, isadvanced by wheels 172 until the leading end of rack 23 engages rollerstop 190 and limit switch LS-3. Actuation of switch LS-3 closes acircuit effecting de-energization or braking of motor 178 to stoprotation of conveyor wheels 172. Switch LS-3 also is effective toinitiate operation of cylinder 146 to elevate lift platform 128 andraise the rack 23 off wheels 172. Another limit switch (not shown)engageable by the lift platform 128 during upward movement thereof aboveconveyor wheels 172 terminates upward movement of the lift platform 128and energizes the circuit controlling operation of motor 122 to advancethe mobile lift apparatus 26 on tracks 27 toward accumulating transferconveyor 21.

The mobile lift apparatus 26 moves longitudinally beneath the active runof conveyor 21 and between the laterally spaced rows of peg assemblies52 until the actuator 167 at the leading end of base frame 111 engageslimit switch LS-2. Actuation of switch LS-2 energizes a circuiteffecting operation of cylinder 158 to retract piston rod 157 and bringhook 155 into engagement with bumper rod 153 for latching the sameagainst abutment pad 151. Switch LS-2 also energizes a time delay relaywhich becomes effective to actuate cylinder 146 and raise the liftplatform 128 further upwardly. The rack 23 moves upwardly on liftplatform 128 between the conveyor frame beams 29, lifting theaccumulated windshield units W off conveyor 21 to an elevationthereabove. As best shown in FIG. 6, the laterally aligned paired pegassemblies 126 of rack 23 lie on a transverse line parallel to butoffset from a line extending through the laterally aligned pegassemblies 52 of conveyor 21 in order to accommodate the curvature ofwindshield units W. Thus, precise positioning of the rack 23 relative toconveyor 21, as effected by the chain centering assembly 66 and thelatch arrangement 153-155, is important in providing a smooth andefficient transfer of the units W from conveyor 21 to rack 23.

As the lift platform 128 approaches the end of its upstroke above thepeg assemblies 52 of conveyor 21, the moving scissor links engage stillanother limit switch (not shown) to stop upward movement of the liftplatform 128 and energize motor 122 to return the mobile lift apparatus26 to its initial position, whereat the lift platform 128 is loweredbelow wheels 172 of the run-in conveyor 25 to deposit the glass ladenrack 23 thereon for conveyance and/or removal off the run-in conveyor25. At the same time, motor 42 is activated to drive accumulatingtransfer conveyor 21 for receiving and accumulating another series ofwindshield units W and the above-described cycle is repeated.

It should be understood that actuation of the several operatingcylinders 71, 81, 95, 146 and 158 is effected by conventional fluidcontrol valves (not shown) properly sequenced for operation by switchesLS-1 and LS-2, as well as other conventional limit switches (not shown)and electrical timers forming part of the electric control system (alsonot shown), which are operated or actuated when predetermined movementsof the various movable parts occur. Each of the switches and/or timerstriggers the subsequent stage of operation of the control valves andconsequent actuation of the several cylinders sequentially. Likewise,energization or braking of the electric motors controlling operation ofconveyors 21, 22 and 25, as well as movement of the mobile liftapparatus 26, also are properly sequenced for operation by limitswitches (including switch LS-1) and timing arrangements forming part ofthe electric control system. The manner of positioning and connectingthe necessary control switches, timers and fluid control valves isconventional and it is believed that no further description oramplification thereof is necessary.

The mode of operation set forth above described the process oftransferring an accumulated series of paired glass sheets from the pegconveyor 21 onto the rack 23. However, it should be appreciated thatthis procedure can be reversed in order to simultaneously transfer anumber of units W from a loaded rack 23 onto a conveyor 21. When theconveyor 21 is employed to receive a plurality of units W from a loadedrack, the mounting of the pads 57 on conveyor 21 is changed to disposethe upright portions 62 thereof just slightly behind the glass engagingfaces of the associated pegs 55a to avoid engagement or interference ofthe glass lower edges with such portions. This is the only changerequired to effect a reversal of the detailed procedure outlined above.Thus, the material handling apparatus 20 of this invention can beutilized to employ an empty rack for stripping articles from a conveyoror for depositing articles from a loaded rack onto a conveyor, asdesired. Moreover, the apparatus 20 is in no way restricted in use topaired sheets of glass or even to glass sheets, but has utility in anymaterial handling operation involving the transfer of somewhat rigidsheet material.

From the foregoing, it is apparent that the objects of the presentinvention have been fully accomplished. A new and useful materialhandling apparatus is provided for rapidly and smoothly transferring aplurality of sheets of material simultaneously from a peg conveyor ontoa novel storage rack or from such storage rack onto a conveyor or otherarticle support system. The conveyor and rack are provided withspecially constructed peg arrangements for accommodating the pluralityof sheets in a spaced, generally upright position. A mobile liftapparatus is provided for moving the rack relative to the conveyor foreffecting the article transfer with the precision required in a fullyautomated, mass production operation.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as an illustrative embodiment only of the same,and that various changes in the shape, size and arrangement of parts, aswell as various procedural changes, may be resorted to without departingfrom the spirit of the invention.

We claim:
 1. A rack especially adapted for supporting a plurality ofcurved glass sheets in a spaced, upright attitude comprising: a frameincluding a pair of longitudinally extending structural members disposedin spaced parallel relation to each other and transversely extendingcross members connecting said longitudinal members together; supportmembers affixed to the upper surfaces of said longitudinal members,respectively, and extending lengthwise thereof; a first row oflongitudinally spaced peg assemblies rigidly secured to one of saidsupport members; a second row of longitudinally spaced peg assembliesrigidly secured to the other of said support members; each of said pegassemblies comprising a pair of pegs extending upwardly from theassociated support member at a slight angle relative to a true verticalin converging relation toward each other; and a pad formed ofresiliently yieldable material affixed to said support member betweeneach adjacent pair of peg assemblies.
 2. A rack according to claim 1,including a cap covering the abutting distal ends of said pegs.
 3. Arack according to claim 2 wherein said cap is formed of a resilientlyyieldable elastomeric material.
 4. A rack according to claim 1 whereinsaid pad is formed with opposite grooves for receiving the lower ends ofopposed pegs of adjacent peg assemblies, respectively.
 5. A rackaccording to claim 1, wherein said peg assemblies of said first row arein lateral alignment with the peg assemblies of said second row.